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  • Title: Resistance of T-cell acute lymphoblastic leukemia to tumor necrosis factor--related apoptosis-inducing ligand-mediated apoptosis.
    Author: Akahane K, Inukai T, Zhang X, Hirose K, Kuroda I, Goi K, Honna H, Kagami K, Nakazawa S, Endo K, Kubota T, Yagita H, Koyama-Okazaki T, Sugita K.
    Journal: Exp Hematol; 2010 Oct; 38(10):885-95. PubMed ID: 20670671.
    Abstract:
    OBJECTIVE: Cytotoxic ligands are involved in tumor immunity and graft-vs.-leukemia effect after allogeneic stem cell transplantation for leukemia. To clarify the susceptibility of T-cell acute lymphoblastic leukemia (T-ALL) to tumor immunity, sensitivity to recombinant human soluble Fas ligand (rhsFasL) and tumor necrosis factor-related apoptosis-inducing ligand (rhsTRAIL) was determined. MATERIALS AND METHODS: Sensitivity to rhsFasL and rhsTRAIL and cell surface expression of their receptors were tested in T-ALL cell lines (n = 7) and patients' samples (n = 17) and compared with those in B-precursor ALL cell lines (n = 30). Expression of components of the death-inducing signaling complex and the TRAIL receptor genes (DR4/DR5), and the methylation status and promoter activity of the DR4/DR5 gene were tested in T-ALL cell lines. RESULTS: T-ALL cell lines showed higher level of Fas expression and higher sensitivity to rhsFasL than did B-precursor ALL cell lines. Despite comparable expression of components of death-inducing signaling complex, cell lines and patients' samples of T-ALL showed TRAIL-resistance associated with low cell surface expression of DR4/DR5. Gene expression of DR4/DR5 in T-ALL cell lines was significantly lower than that in B-precursor ALL cell lines, and the methylation status of the gene promoter in T-ALL cell lines was associated with the gene expression level at least for DR4. The demethylating agent, 5-aza 2'deoxycytidine, upregulated the gene expression of DR4/DR5, but was insufficient for their surface expression due to low basal promoter activity. CONCLUSIONS: In contrast to higher sensitivity to FasL, T-ALL showed resistance to TRAIL, which might be responsible for resistance to TRAIL-mediated cellular immunity.
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